Removing rear AC lines at evaporator

Discussion in 'Engine & Drivetrain' started by KVacek, Jun 5, 2018.

  1. KVacek

    KVacek TYF Newbie

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    2005 Yukon Denali XL
    Need to replace the seals at the rear evaporator connection, under the vehicle, but cannot get the connections free. Nuts came off fine and I've tried heat and penetrant, but the connection aluminum blocks are seized on their studs. Asked a great independent shop, he said nobody can get them off. Had a local automotive radiator and A/C shop try but they gave up too.

    I have a set of new lines on the way (I'll eventually need them anyway I'm sure), but is there any trick I should try first to get these off intact?
     
  2. sumo

    sumo dn ʇǝƃ ʇuɐɔ & llǝɟ ı

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    Forget about it. I broke mine too and ended up having to order a New rear Evap. I even had my old one benched and did everything to try and separate it.
     
  3. KVacek

    KVacek TYF Newbie

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    Ummmm, thanks for the bad news ;-) As I figured...
    To get the old connectors off the evaporator I was just going to slice across the aluminum along the stud. Gotta come off then, doesn't it?
     
  4. KVacek

    KVacek TYF Newbie

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    They weren't seized on the studs as much as the seals having welded themselves onto both parts.

    If you need to do this job, it's probably not as hard as it seems. After lots of heat and dry ice (thermal cycling), and a trip to an A/C shop that couldn't get the lines off either, I persisted and eventually got them off. The corrosion in the stud holes through the connectors was likely not a real issue, though heat cycling probably helped break it loose.

    First one came off with lots of heat, which appeared to mostly melt the seal. The second one came off with lots of trichlotoethane (Brakleen), which is a good solvent for the HNBR seals, and ate the rubber seal loose. I did pry a bit. Cleaned up with Brakleen, a brass brush, and ScotchBrite. New seals with blue Nylog, lots of antiseize on the studs, vacuumed and charged, 1 oz of PAG 46 oil for good measure, and it's fine. Cold A/C.

    I had ordered a set of new lines (from an advertiser on this forum) figuring I'd have to cut off these connectors, but the lines came later than promised and I'd already given up on them coming in time. Package unopened, going back tomorrow.
     
    Last edited: Jun 10, 2018

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